/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package io.minio.org.apache.commons.validator.routines;

import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
import java.io.Serializable;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * <b>Regular Expression</b> validation (using JDK 1.4+ regex support).
 *
 * <p>Construct the validator either for a single regular expression or a set (array) of regular
 * expressions. By default validation is <i>case sensitive</i> but constructors are provided to
 * allow <i>case in-sensitive</i> validation. For example to create a validator which does <i>case
 * in-sensitive</i> validation for a set of regular expressions:
 *
 * <pre>
 * <code>
 * String[] regexs = new String[] {...};
 * RegexValidator validator = new RegexValidator(regexs, false);
 * </code>
 * </pre>
 *
 * <p>
 *
 * <ul>
 *   <li>Validate <code>true</code> or <code>false</code>:
 *   <li>
 *       <ul>
 *         <li><code>boolean valid = validator.isValid(value);</code>
 *       </ul>
 *   <li>Validate returning an aggregated String of the matched groups:
 *   <li>
 *       <ul>
 *         <li><code>String result = validator.validate(value);</code>
 *       </ul>
 *   <li>Validate returning the matched groups:
 *   <li>
 *       <ul>
 *         <li><code>String[] result = validator.match(value);</code>
 *       </ul>
 * </ul>
 *
 * <p><b>Note that patterns are matched against the entire input.</b>
 *
 * <p>
 *
 * <p>Cached instances pre-compile and re-use {@link Pattern}(s) - which according to the {@link
 * Pattern} API are safe to use in a multi-threaded environment.
 *
 * @version $Revision$
 * @since Validator 1.4
 */
public class RegexValidator implements Serializable {

  private static final long serialVersionUID = -8832409930574867162L;

  private final Pattern[] patterns;

  /**
   * Construct a <i>case sensitive</i> validator for a single regular expression.
   *
   * @param regex The regular expression this validator will validate against
   */
  public RegexValidator(String regex) {
    this(regex, true);
  }

  /**
   * Construct a validator for a single regular expression with the specified case sensitivity.
   *
   * @param regex The regular expression this validator will validate against
   * @param caseSensitive when <code>true</code> matching is <i>case sensitive</i>, otherwise
   *     matching is <i>case in-sensitive</i>
   */
  public RegexValidator(String regex, boolean caseSensitive) {
    this(new String[] {regex}, caseSensitive);
  }

  /**
   * Construct a <i>case sensitive</i> validator that matches any one of the set of regular
   * expressions.
   *
   * @param regexs The set of regular expressions this validator will validate against
   */
  public RegexValidator(String[] regexs) {
    this(regexs, true);
  }

  /**
   * Construct a validator that matches any one of the set of regular expressions with the specified
   * case sensitivity.
   *
   * @param regexs The set of regular expressions this validator will validate against
   * @param caseSensitive when <code>true</code> matching is <i>case sensitive</i>, otherwise
   *     matching is <i>case in-sensitive</i>
   */
  public RegexValidator(String[] regexs, boolean caseSensitive) {
    if (regexs == null || regexs.length == 0) {
      throw new IllegalArgumentException("Regular expressions are missing");
    }
    patterns = new Pattern[regexs.length];
    int flags = (caseSensitive ? 0 : Pattern.CASE_INSENSITIVE);
    for (int i = 0; i < regexs.length; i++) {
      if (regexs[i] == null || regexs[i].length() == 0) {
        throw new IllegalArgumentException("Regular expression[" + i + "] is missing");
      }
      patterns[i] = Pattern.compile(regexs[i], flags);
    }
  }

  /**
   * Validate a value against the set of regular expressions.
   *
   * @param value The value to validate.
   * @return <code>true</code> if the value is valid otherwise <code>false</code>.
   */
  public boolean isValid(String value) {
    if (value == null) {
      return false;
    }
    for (int i = 0; i < patterns.length; i++) {
      if (patterns[i].matcher(value).matches()) {
        return true;
      }
    }
    return false;
  }

  /**
   * Validate a value against the set of regular expressions returning the array of matched groups.
   *
   * @param value The value to validate.
   * @return String array of the <i>groups</i> matched if valid or <code>null</code> if invalid
   */
  @SuppressFBWarnings(
      value = "PZLA",
      justification = "Null is checked, not empty array. API is clear as well.")
  public String[] match(String value) {
    if (value == null) {
      return null;
    }
    for (int i = 0; i < patterns.length; i++) {
      Matcher matcher = patterns[i].matcher(value);
      if (matcher.matches()) {
        int count = matcher.groupCount();
        String[] groups = new String[count];
        for (int j = 0; j < count; j++) {
          groups[j] = matcher.group(j + 1);
        }
        return groups;
      }
    }
    return null;
  }

  /**
   * Validate a value against the set of regular expressions returning a String value of the
   * aggregated groups.
   *
   * @param value The value to validate.
   * @return Aggregated String value comprised of the <i>groups</i> matched if valid or <code>null
   *     </code> if invalid
   */
  public String validate(String value) {
    if (value == null) {
      return null;
    }
    for (int i = 0; i < patterns.length; i++) {
      Matcher matcher = patterns[i].matcher(value);
      if (matcher.matches()) {
        int count = matcher.groupCount();
        if (count == 1) {
          return matcher.group(1);
        }
        StringBuilder buffer = new StringBuilder();
        for (int j = 0; j < count; j++) {
          String component = matcher.group(j + 1);
          if (component != null) {
            buffer.append(component);
          }
        }
        return buffer.toString();
      }
    }
    return null;
  }

  /**
   * Provide a String representation of this validator.
   *
   * @return A String representation of this validator
   */
  @Override
  public String toString() {
    StringBuilder buffer = new StringBuilder();
    buffer.append("RegexValidator{");
    for (int i = 0; i < patterns.length; i++) {
      if (i > 0) {
        buffer.append(",");
      }
      buffer.append(patterns[i].pattern());
    }
    buffer.append("}");
    return buffer.toString();
  }
}
